Stuffer box crimper with composite crimper discs



' March 1, 1966 3,237,270

STUFFER BOX CRIMPER WITH COMPOSITE GRIMPER nIscs F. s. DENNIS Filed Dec. 11 1965 1 NVEN TOR F260 $777/VL5Y MAM/As,

mlllllll BY Mm flGEA/T United States Patent 3,237,270 STUFFER BOX CRIMPER WITH COMPOSITE CRIMPER DISCS Fred Stanley Dennis, Kinston, N.C., assignor to E. I. du

Pont de Nemours and Company, Wilmington, Del., a

corporation of Delaware Filed Dec. 11, 1963, Ser. No. 329,684 6 Claims. (Cl. 28-1) This invention relates to apparatus for crimping synthetic filamentary tow and more particularly to means for extending the useful life of a stutter-box crimper. Still more particularly, this invention relates to a novel composite crimper disc.

The composite crimper disc of this invention can be advantageously utilized in the stuffer-box crimper disclosed by Hitt in US. Patent 2,311,174, dated February 1 6, 1943, which also recognizes the desirability of installing crimper discs at each side of and below the line of contact (nip) of the two crimping rolls to control the path of tow from the nip of the rolls into the stuffer box. To prevent entanglement of filaments between the ends of the crimper rolls and the crimper discs, it is necessary that a firm, rubbing contact between the ends of the rolls and the crimper discs be maintained. The use of crimper discs comprising a relatively hard material such as a ceramic results in an unacceptable rate of wear on the edges of the crimper rolls whereas the use of a relatively soft material disc such as phosphor bronze entails frequent interruption of the process to replace discs worn by the abrasive action of compressed filamentary tow passing over their surface. Also, attempts to employ solid, synthetic polymeric crimper discs of generally accepted lubricous and abrasion-resistant characteristics were not entirely successful due to the poor thermal conductivity which resulted in the fusion of filaments near the edges of the crimped tow.

An object of this invention is to provide a crimper disc which has low abrasiveness with respect to the ends of the crimper rolls. A further object is to provide a crimper disc which has high resistance to the abrasive action of compressed filamentary tow. Other objects will become apparent from the specification and claims.

The objects of this invention are accomplished by a composite crimper disc composed of a relatively soft material shell having a Rockwell hardness of less than about F-80 and a relatively hard material insert having a hardness of at least 200 Brinell which is positioned in the area which will receive the greatest compressive loading by the filamentary tow in use. i

More particularly, the relatively soft material shell can be a bronze comprising approximately, by weight, 85% copper, 5% tin, 5% zinc and 5% lead, which is free of oxygen, and is machined to form a cavity in the area which will receive the greatest compressive loading. The hard material insert can be a cast iron shaped to fit and pressed into the cavity, the final assembly being machined to the desired flatness and smoothness tolerances. The working surface in contact with the crimper rolls can be coated with a lubricous material, such as a polyfiuorocarbon enamel, to provide effective lubrication with the crimper rolls. It is preferred not to coat the area in contact with the filamentary tow due to the abrasiveness of most synthetic filamentary tows under compressive loading.

In the drawings, which illustrate the invention and apparatus discussed hereinafter:

FIGURE 1 is an elevation view of a stutter-box crimper, partially in cross-section, the section being taken as indicated by line 1--1 in FIGURE 2;

FIGURE 2 is a cross-sectional view taken along the line 22 of FIGURE 1;

FIGURES 3 and 4 are details of the composite crimper disc with the insert of a harder material.

With reference to FIGURE 1, synthetic filamentary tow 1 is forwarded into contact with crimping rolls 2 and 3 and into stuffer box 4. Crimping roll 3 is driven by means not shown and crimping roll 2 is an idler, urged into contact with the tow by means schematically represented by spring 5. The approach of crimper roll 2 toward crimping roll 3 may be limited by adjustable stop 6. Clapper 7 restricts egress of the crimped tow from the stulfer box, which requires that the synthetic filamentary tow 1 be placed under high compression at the nip of crimping rolls 2 and 3 in order to be forwarded into stuifer box 4. Lateral egress of synthetic filamentary tow 1 between the nip and the entrance of the stuffer box 4 at Wiper blades 8 and 9 is prevented by the presence of composite crimper discs 10, inserts 11 of harder materials being positioned as indicated. FIGURE 2 is a vertical cross-sectional view taken along line 22 of FIGURE 1 and shows the positioning of crimper discs 10 in relation to crimper rolls 2 and 3, the inserts 11 being positioned in the area of greatest compressive contact with the tow. FIGURES 3 and 4 are details of crimper discs 10 and show the shape of the preferred embodiment with the harder material insert 11.

The composite crimper discs of this invention can be composed of various soft material shells such as bronze compositions, aluminum and copper, which have hardnesses below Rockwell F-80. For the hard material insert, various grades of cast iron with low friction and self-lubricating characteristics and a hardness of at least 200 Brinell have been found to be suitable. For optimum performance, the thermal conductivity and coefficient of thermal expansion should closely approximate that of the soft material shell. Suitable lubricous coatings for the soft material shell include Teflon (tetrafluoroethylene-fluorocarbon resin), Trademark Registration No. 418,698, dated January 18, 1946, by E. I. du Pont de Nemours and Co., Vydax (fluorocarbon telomers), Trademark Registration No. 707,084, dated November 15, 1960 by E. I. du Pont Nemours and C0., other low molecular weight fluorocarbon resins, nylons, Lexan (polycarbonate resin), Trademark Registration No. 637,022, dated November 13, 1956 by the General Electric 00., aromatic polyimides and thermoset epoxy and phenolic resins. Oil-impregnated bronze is also suitable.

It is preferred to employ a circular insert due to the convenience in fabrication as well as orientation relative to the crimper rolls. However, other insert shapes can also be used and are Within the contemplation of this invention.

The present invention provides a simply-fabricated and easily installed crimper disc which is effectual in the reduction of wear rate by synthetic filamentary tow. The wear observed on the soft material shell of the composite crimper disc downstream (relative to travel of the tow) from the harder material insert has been found to be substantially less than the observed in the same area when using discs of all-bronze construction. Wear in the critical central area of the composite crimper disc, where compressive, rubbing contact with the tow is greatest, has been found to occur at A to the rate experienced with all-bronze discs.

Since many different embodiments of the invention may be made without departing from the spirit and scope there of, it is to be understood that the invention is not limited by the specific illustrations except to the extent defined in the following claims.

What is claimed is:

1. In a crimper for synthetic filamentary tow having cooperating crimper rolls, a stuffer box associated with said crimper rolls to accommodate the entry of said synthetic filamentary tow and crimper discs positioned on each side of and below the nip of said crimping rolls so that the central portion of said crimper discs receive the greatest compressive contact with said synthetic filamentary tow, the improvement comprising composite crimper discs consisting of a soft material shell having a Rockwell hardness of less than about F-80 and selected from the group consisting of bronze, aluminum and=c0pper and a harder material insert positioned in the central portion of said soft material shell, said insert consisting of cast iron having a hardness of at least 200 Brinell.

2. The composite crimper discs of claim 1 wherein said soft material shell consists of aluminum.

3. The composite crimper discs of claim '1 wherein said soft material shell consists of bronze.

4. The composite crimper discs of claim 1 wherein said soft material shell consists of copper.

5. The composite crimper discs of claim 1 wherein said insert is circular in shape.

6. The composite crimper discs of claim 1 wherein said soft material shell is coated with a thin lubricous coating of a member selected from the group consisting of fluorocarbon resins, polycarbonate resins, aromatic polyimides and thermoset epoxy and phenolic resins.

References Cited by the Examiner UNITED STATES PATENTS 2,311,174 2/1943 I-Iitt a 19-66 2,933,771 4/1960 Weinstock 28-72 3,113,667 12/ 1963 McGill 28-1 3,120,692 2/1964 Crawford et al 28-72 3,160,941 12/1964 Williamson 28-1 FOREIGN PATENTS 816,778 7/1959 Great Britain.

DONALD W. PARKER, Prima'ry Examiner. 

1. IN A CRIMPER FO SYNTHETIC FILAMENTARY TOW HAVING COOPERATING CRIMPER ROLLS, A STUFFER BOX ASSOCIATED WITH SAID CRIMPER ROLLS TO ACCOMMODATE THE ENTRY OF SAIDY SYNTHETIC FILAMENTARY TOW AND CRIMPR DISCS POSITIONED ON EACH SIDE OF AND BELOW TH ENIP OF SAID CRIMPING ROLLS SO THAT THE CENTRAL PORTION OF SAID CRIMPER DISCS RECEIVE THE GREATEST COMPRESSIVE CONTACT WITH SAID SYNTHETIC FILAMENTARY TOW, THE IMPROVEMENT COMPRISING COMPOSITE CRIMPER 